Vulcanizable composition containing sulfur, rubber, and an alkenylthiophenol



I ma.-.

VULCANIZABLE COMPOSITION CONTAINING SULFUR, RUBBER, AND AN ALKENYLTHIO-PHENDL Herman S. Bloch, Chicago, EL, assignor, by mesne assignments, toUniversal Gil Products Company, Des

Plaines, 111., a corporation of Delaware No Drawing. ApplicationDecember 11, 1953 Serial No. 397,764

7 Claims; (Cl. 260- This application is a continuation-in-part of mycop'ending'application Serial N0. 240,034, filed August 2, 1951, now US.Patent No. 2,662,869, which is itself a continuation-impart of mycopending application Serial No. 673,482, filed May 31, 1946, nowabandoned.

This invention relates to a bonding composition suitable for joiningmetal, wood, glass, and a thermosetting resin to each other or forjoining pieces of one of these materials. 7

An object of this invention is to form a vulcanizable bondingcomposition by interacting unsaturated compounds and aromatic compounds.

Another object of this invention is to form a bonding compositionbyvulcan'izing a mixture comprising a copolymer of butadiene and styreneand a material formed by interacting isoprene and a thiophenol in thepresence of an acid catalyst.

One embodiment of this invention relates to a bonding compositioncomprising sulfur, an unsaturated elastomer selected from the groupconsisting of natural rubber and a rubbery copolymer, and a condensationproduct of a thiophenol with a conjugated diolefin hydrocarbon.

Another embodiment of this invention relates to a bonding compositioncomprising sulfur, an unsaturated elastomer selected from the groupconsisting of natural rubber and a rubbery copolymer, and analkenylarylthio ether condensation product of a thiophenol with aconjugated diolefin hydrocarbon.

A further embodiment of this invention relates to a bonding compositioncomprising sulfur, a rubbery copolymer of butadiene and styrene, and acondensation product of from about 0.25 to about molecular proportionsof a thiophenol with one molecular proportion of a conjugated diolefinhydrocarbon selected from the group consisting of butadiene andisoprene.

A bonding composition suitable for joining concrete, stone, wood, metal,etc., with glass, tile, thermose'tting resins, plastics, etc., comprisesa vulcanizable material made by reacting a polyenic material such as adienic or polyenic hydrocarbon or derivative thereof, such as butadiene,isoprene, chloroprene, piperylene, cyclopentadiene, etc., and asubstituted aromatic compound selected from thiophenol, thiocresols, andother simple derivatives of thiophenol itself. These reaction productsin clude such materials as alkenylthiophenols, alkenylarylthioethers,di-alkenylated thiophenols,heterocyclic com pounds such as thiachromansand thiacoumarans, resinous alkenylated thiophenol condensationproducts, alkenylthiocresols, alkenylcresylthioethers, di-alkenylated.thiocresols, resinous alkenylated thiocresol condensation products,etc.

The reaction products include also the condensation products of thematerials with aldehydes or ketones, for example with formaldehyde;theproducts produced by the polymerization of the materials; and thehigh molecular weight polymeric and condensation products formed as aresinous bottoms by-product in the preparation of the materials.

The preparation of successful bonding agents applicable to the bondingof the materials of widely dissimilar characteristics discussed above,involves consideration of the following principles: 1) the bonding agentshould be capable of setting at a relatively low temperature, so as notto destroy materials which, like Wood, are relatively heat unstable; (2)the agent should contain ingredients capable of establishing firm bondswith polar materials such as wood or glass; (3) it should containingredients capable of establishing firm bonds with metals; (4)ingredient (2) should be the same as that of ingredient (3) or becapable of forming a stable compound with it.

Alkenylphenylthioethers and other related condensation products of athiophenol and a conjugated diolefin which may be used as a startingmaterial in this process may be obtained by reacting one molecularproportion of a conjugated diolefin with from about 0.25 to about 5molecular proportions of a thiophenol in the presence of an acidcatalyst at condensation conditions. Suitable acid catalysts include aphosphoric acid, a composite of a phosphoric acid and an ether, acomposite of a phosphoric acid and a siliceous adsorbent precalcined ata temperature of from about 250 to about 600, an acidactiug metalphosphate, and the like. The phosphoric acid containing catalysts areemployed at a temperature of from about 25 to about 300 C. and at apressure of from about substantially atmospheric to about 150atmospheres or more.

Condensation of a conjugated diolefin with a thiophenol may be carriedout by mixing a diolefinic hydrocarbon with an excess of the thiophenoland then passing the resultant mixture or solution in the presence orabsence of a non-polar diluent, such as a paraflinic hydrocarbon ornaphthenic hydrocarbon, through a suitable tower or reactor containingformed particles of a solid phosphoric acid catalyst or acid phosphatecatalyst maintained at a temperature of from about 25 to about 300 C.,and preferably at a temperature of from about to about 250 C. Thereaction is also carried out at a pressure of substantially atmosphericto about 150 atm'ospher'es or more, the pressure generally beingsuflicient to maintain a substantial proportion of the reactants inliquid phase.

The step of condensing a thiophenol with a diolefin may also be carriedout in a batch type operation by adding the diolefin continuously to astirred mixture of the thiophenol and a liquid catalyst such asorthophosphoric acid, or a complex of a concentrated phosphoric acid andan ether, such as a complex of .orthophosphoric acid and substantiallyanhydrous diethyl ether.

The products so formed by reacting a conjugated diolefin and athiophenol in the presence of a phosphoric acid "catalyst are separatedinto a catalystlayer and an organic product layer, the latter beingseparated into the unreacted thiophenol and reactionproducts. Thereac'tion products may be fractionally distilled to separate lowerboiling products from higher boiling residue or I substantially neutralcondensation products such as thioethers, heterocyclic products, resins,etc. The condensation product which is soluble in caustic soda solutionis then recovered as an oily layer by neutralizing the caustic sodasolution with an acid or by reacting the caustic soda solution withcarbon dioxide so as to liberate dissolved thiophenols such as thealkenylthiophenols together with some unconverted thiophenolic startingmaterials. The mixture of the thiophenol and alkenylthiophenols soobtained is then subjected to fractional distillation in order toseparate unconverted starting materials, monoalkenylthiophenols such asbutenyl thiophenols or pentenylthiophenols, and higher boilingcondensation products. Similarly, the alkali-insoluble material may befractionated to separate the monoalkenylated product (mainlyalkenylarylthioethers), the dialkenylated products, and higher-boilingresidues. Alternatively, the mixed alkenylation products, or fractionsthereof, may be used without prior separation of caustic: soluble fromcaustic-insoluble components.

in the case of bonding compositions formed by 'vul-' canizing compositesof butenyl or pentenylthiophenols or the isomeric thioethers, or theresidues formed in the preparation of butenyl or pentenylthiophenols bythe alkenylation of thiophenol with butadiene or isoprene in thepresence of phosphoric acid, the presence of residual unsaturationpermits vulcanization of the material with' sulfur at temperatures offrom about 125 to about 200 C. This vulcanization treatment is carriedout for a time of from about 0.5 to about 10 hours. The thio phenolgroups are capable of firm attachment to polar materials, for example,by hydrogen bonding with the oxygen of the hydroxy groups of cellulosicmaterials or with the oxygen in glass. The unsaturated linkages arecapable of forming firm bonds with metals probably by way of the sulfurused in vulcanization. Finally, if the butenylthiophenol derivative orother alkenylthiophenol derivative is used alone, or if it is used inconjunction With some other vulcanizable material, for example rubber,which bonds two metals via sulfur, the butenylthiophenol compounds orother alkenylthiophenol compounds are capable of linking with the rubberby copolymerization, by covulcanization, or by the formation ofthiachroman or thiacourmaran rings. 1

The thiophenol-conjugated diene reaction products, or their aldehydecondensation products, with sulfur and the conventionally usedaccelerators or other additives such as carbon black, zinc oxide and thelike, may be used with or without vulcanizable elastomeric materialscontaining double bonds, such as natural or synthetic rubber, forexample, butadiene-styrene copolymers, to form a heat curableall-purpose bonding agent. Since in the milling of these materials withrubber, the material may stick to the rolls it may be desirable also toincorporate additional plasticizers or solvents in such compositions. Ifnatural or synthetic rubber comprises part of the bonding composition,the diene-thiophenol condensation product may be used in an amountcomprising from about 5 to about 50% of the bonding composition,although generally from about 10% to about 25% is most satisfactory.

The following example is given to illustrate the type of bondingcomposition referred to above, although the data presented are notincluded with the intention of restricting unduly the generally broadscope of this invention.

At atmospheric pressure, over a three-hour period 123.7 grams ofisoprene was dropped into a stirred mixture of 570 grams of .thiophenoland 91.2 grams of 100% orthophosphoric acid. During this three-hourperiod the temperature of the mixture was maintained at 85-90 C.

At the completion of the addition period, the stirring was maintainedfor an additional one-half hour at 85-90 C., after which time thereaction mixture was allowed to cool. The isoprene was completelyabsorbed. Upon elimination of the phosphoric acid, the resultant product4 '1. was subjected to fractional vacuum distillation to give thefollowing results:

Boiling Pt., 0. Grams Percent Unreacted thiophenol /21 mm 298 43 Mixtureof unreacted thiophenol -125/21 mm 6. 2 1

and monoallrenylation product. Mtonopentenylthiophenol frac- 123-129/14mm. 193. 7 28 1011. Mixture of pcntenylthiophenol 7680/% mm 20 3 anddipentcnylthiophenol. Dipentenylthiophenol fraction 160170/% mm..." 75.3 l1 Rcsinous bottoms Over 170/ 36mm... :10 1 5 Unaccouuted for loss 89.8

parts by weight of a rubbery butadiene-styrene copolymer (GR-S), 50parts by Weight of carbon black (Kosmobile-77), 20 parts by weight ofthe pentenylphenylthioether (caustic insoluble fraction), 5 parts byweight of zinc oxide, 5 parts by weight of sulfur, and 1.5 parts byweight of Z-mercaptobenzothioazole, are mixed on a rubber mill to form ahomogeneous rubber like mass.

The material mixed on the rubber mill is then vulcanized between twooverlapping pieces of soft steel (0.8 mm. thick) at a temperature of C.and under a pressure of 1,000 p.s.i. for 50 minutes. The vulcanizedmaterial forms a firm bond with the steel, thus firmly cementingtogether the two steel strips in this test.

The dipentenylthiophenol' caustic soluble fraction is employed in thefollowing formulation which is milled as described above:

Parts GR-S 100v Kosmobile-77 50 Dipentenylthiophenol fraction 20, Sulfur4 Zinc oxide 5 2-mercaptobenzothiazole 15 natural rubber and a rubberycopolymer, and an alkenyh phenylthioether condensation product ofathiophenol' with'a conjugated diolefin hydrocarbon.

3. A bonding composition comprising sulfur, an unsaturated elastornerselected from the group consisting of natural rubber and a robberycopolymer, and a resinous condensation product of a thiophenol with aconjugated diolefin hydrocarbon. 4.- A bonding composition comprisingsulfur, an unsaturated elastomer selected from the group consisting ofnatural rubber and a rubbery copolymer, and a condensation product offrom about 0.25 to about 5 molecular proportions of a thiophenol withone molecular proportion of a conjugated diolefin hydrocarbon.

5. A bonding composition comprising sulfur, an unsaturated elastomerselected from the group consisting of natural rubber and a rubberycopolymer, and an alkenylphenylthioether condensation product of fromabout 0.25 to about 5 molecular proportions of a thiophenol with onemolecular proportion of a conjugated diolefin hydrocarbon.

6. A bonding composition comprising sulfur, an unsaturated elastomerselected from the group consisting of natural rubber and a rubberycopolymer, and a resinous condensation product of from about 0.25 toabout 5 molecular proportions of a thiophenol with 1 molecularproportion of a conjugated diolefin hydrocarbon.

5 with a conjugated diolefin hydrocarbon.

References (lited in the file of this patent UNITED STATES PATENTS 102,316,949 Garvey Apr. 20, 1943 2,325,981 Sarbach Aug. 3, 1943 2,337,464Hecht Dec. 21, 1943 2,443,811 Winkler June 22, 1948 2,476,824 AlbertJuly 19, 1949 15 2,662,869 Bloch Dec. 15, 1953

1. A BONDING COMPOSITION COMPRISING SULFUR, AN UNSATURATED ELASTOMER SELECTED FROM THE GROUP CONSISTING OF NATURAL RUBBER AND A RUBBERY COPOLYMER AND A CONDENSATION PRODUCT OF A THIOPHENOL WITH A CONJUGATED DIOLEFIN HYDROCARBON. 